Piping structure for oil tanker

ABSTRACT

An ore/coal carrier is provided with piping passages  42  of watertight structure and of substantially rectangular cross section. The passage is located between longitudinal bulkheads  32  and cargo hatches  38 , and extends within an upper portion of central cargo oil tanks  34 . Two of cargo oil delivery pipes  50  leading from a pump room to a shore connection  48  at midship portion of a hull are passed through a starboard piping passage, and the remaining one is passed through a port passage. The starboard passage extends up to the central portion of the hull, however, the port one extends close up to a bow, and an inert gas pipe  58  is passed through in the port passage.

TECHNICAL FIELD

The present invention relates to oil tankers in a broad sense, namely pure oil tankers and convertible oil tankers capable of loading solid cargo such as ore or coal as well. More particularly it relates to their piping structures for cargo oil and other pipes.

BACKGROUND ART

FIG. 8( a) shows one known oil tanker, in which cargo oil pumps 17 are provided in a pump room 16 in front of an engine room 18. Cargo oil suction pipes 57 interconnect the cargo pump 17 and each of cargo tanks; cargo oil delivery pipes 50 interconnect the pump 17 and shore connections 48 provided amidship on an upper deck. In cargo oil unloading, cargo oil in the respective oil tanks is sucked through the cargo oil suction pipe 57 into the cargo pump 17, then sent through the cargo oil delivery pipe 50 to the shore connection 48, and is delivered to a reception facility on shore. Cargo oil suction pipes 57 are passed as low as possible in the cargo tanks to improve suction efficiency, However, cargo oil delivery pipes 50 are raised from the pump room up to an upper deck 30 and extends on the upper deck to the midship portion of the hull.

In the above mentioned piping arrangement, the cargo oil delivery pipes 50 running on the upper deck may be exposed to spray from sea water waves, and susceptible to corrosive damage, resulting in much maintenance costs.

Further, since cargo oil delivery pipes are normally large in diameter, the existence of the pipes on upper deck may obstruct the worker's traffic particularly in transverse direction of the ship.

In Patent Documents 1 and 2, it is proposed that the cargo oil delivery pipes 50 should be passed within cargo oil tanks, at midship raised above the upper deck, and then connected to the shore connection 48 as shown in FIG. 8( b). Such pipe arrangement can make the upper deck free of the cargo oil delivery pipe 50, thus eliminating pipe corrosion by sea spray and an obstruction to worker's traffic on the upper deck.

However, in the conventional oil tankers, pipes which may obstruct traffic on an upper deck are not only cargo oil delivery pipes but also a fuel oil loading pipe, a cargo oil stripper pipe, a fire main pipe, a tank cleaning pipe, an electric wire duct pipe, and so on. Further, in order to prevent an explosion accident, recent large tankers are provided with an inert gas system. The system has an inert gas generator disposed aft portion of the hull, from which an inert gas main pipe extends forward on upper deck, resulting in obstruction to traffic on the upper deck.

Particularly in convertible oil tankers capable of loading ore and bulk as well, cargo hatches on the upper deck will make the traffic problems more difficult. In addition, during unloading ore or coal, part of it is may spilled on the deck, therefore, on-deck piping requires protective covers. However, spilled ore or coal is apt to collect under the protective cover, thus requiring troublesome work for deck cleaning.

Accordingly, only by passing the cargo oil delivery pipes within cargo oil tanks it is difficult to overcome the problems of on-deck traffic, deck cleaning, corrosion and deterioration of on-deck pipes.

Patent Document 1: Japanese Utility Application Laid-open No. Sho 55-107498 Patent Document 2: Japanese Patent Application Laid-open No. Hei 08-295288

DISCLOSURE OF THE INVENTION

The object of the present invention is to solve such problems in pure or convertible oil tankers.

According to the present invention there is provided a taker having a piping passage longitudinally extending within a hull of the tanker. A cargo delivery pipe is run through in said passage to interconnect a pump room at an aft portion of the hull and a shore- connection provided amidship on the upper deck. The passage is surrounded by watertight structures and particularly an inside top portion thereof is formed by the upper deck.

By providing the piping passage under the upper deck for housing cargo delivery pipes, it is possible to minimize the possibility of the oil flowing down into the sea in the event of oil leakage in the cargo delivery pipe. In addition the upper deck can be kept free of the cargo oil delivery pipes, it is easy for workers or carts to move on the upper deck. Further, the cargo oil delivery pipes within the piping passage are not exposed to spray from sea water waves, thus preventing corrosive damage and maintenance costs reduced.

Not only the cargo oil delivery pipes but also almost all of pipes running longitudinally along on the upper deck in the conventional tanker can be passed through the piping passage. Such pipes may include an inert gas pipe, a tank cleaning pipe, a fire main pipe, an electric wire pipe, a cargo oil stripper pipe, and a fuel oil loading pipe. This arrangement may solve the problems of on-deck traffic, deck cleaning, and corrosion of the pipes. The pipes such as the inert gas pipe, the tank cleaning pipe, and the fire main pipe are run near to a bow part, therefore, the piping passage housing these pipes have to also extend near to the bow.

Preferably the piping passage is arranged in contact with longitudinal bulkheads for dividing the inside of the hull into the oil tanks in rows or in contact with a side ballast tank, In this arrangement, hull structure members can serve as a part of walls of the piping passage. Thus the amount of structural material and building cost can be saved.

The piping passage is preferably fitted with some doorways leading to the upper deck. The inside of the passage have enough space for worker to pass through it. And also, it is preferable that the piping passage is equipped with a ventilator, a gas detector, a sprinkler system, and the like to provide for gas explosion or fire.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of an ore/oil carrier;

FIG. 2 is a plan view of the ship of FIG. 1;

FIG. 3 is a sectional view along the line 3-3 shown in FIG. 2;

FIG. 4 is a sectional view along the line 4-4 in FIG. 2;

FIG. 5 is a midship sectional view of another ore/oil carrier;

FIG. 6 is a midship sectional view of a pure oil tanker;

FIG. 7 is a midship sectional view of an oil/ore/bulk carrier; and

FIG. 8 is a cargo piping arrangement of prior art oil tankers,

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIGS. 1 and 2, a hull space of an ore/oil carrier is divided by transverse bulkheads 10, into a bow portion 12, a cargo space 14, a pump room 16, an engine room 18, and a stern portion 20. An accommodation space 22 is located on the engine room 18 and a wheelhouse 24 is thereon.

As shown in FIG. 3, the cargo space 14 has a double hull structure at both of hull bottom and hull sides, and insides of them form ballast tanks 26, 28. The cargo space surrounded by these double hull structures and an upper deck 30 is divided by two longitudinal bulkheads 32 into central cargo oil tanks (or ore hold) 34 and wing cargo oil tanks 36. Just above each of central cargo oil tanks 34, cargo hatch 38 is provided on the upper deck 30, and the hatch is equipped with an oil-tight hatch cover 40.

Water-tight piping passages 42 with almost rectangular cross sections are extending longitudinally within an upper portion of the central cargo oil tank 34. The passage is located between the longitudinal bulkheads 32 and cargo hatches 38, the upper side of the passage 42 is defined by the upper deck 30; the outer and inner sides thereof are defined by a longitudinal bulkhead 32 and a hatch side girder 46, respectively. Hull structure members 32, 46 serve as side walls of the piping passage so that the passage can be built at reduced costs.

In prior art oil tankers, many pipes run longitudinally on upper deck, however, most of such pipes can be housed in the passages 42 formed under the upper deck. As shown in FIG. 2, two piping passages extend forward from the pump room 16, but are different in length; the starboard side passage extends up to the midship, while the port one up to the bow.

To interconnect the pump room 16 and shore connections 48 at a midship there are provided a total of three cargo delivery pipes 50, two of which extend in the starboard side passage, and the remaining one extends through the port side passage as shown in FIG. 3. The shore connections 48 at the starboard and port sides are interconnected with crossover pipes 52, and the cargo delivery pipes 50 extending in passages are drawn out up to the upper deck at midship and connected to the crossover pipes 52.

Some pipes 54 including a fuel oil loading pipe and a cargo oil stripper pipe are passing through the starboard passage 42 and connected to the shore connection 48.

When cargo tanks become negative pressure while unloading of cargo or at sea, cargo tanks are supplied with inert gas obtained by treating boiler's exhaust gas so as to reduce the possibility of cargo tank's explosion. Inert gas supply pipe 58, which have big diameter like the cargo oil delivery pipe 50, are passed through the port passage to the bow. As shown in FIG. 4, branch pipes 60 branching off from the inert gas pipe 58 run above the upper deck and reach the respective cargo oil tanks 34, 36.

In addition to the cargo oil delivery pipe 50 and the inert gas pipe 58, some pipes 62 including a tank cleaning pipe, a fire main pipe and an electric wire pipe pass through the port passage and extend to the bow portion as shown in FIG. 3 and FIG. 4,

In order to access to the piping passage 42 from the upper deck 30 for valve operations and a maintenance of piping, access hatches 68 having watertight covers are provided. Passages 42 are preferably sufficiently large to permit workers to pass through.

Passages 42 are preferably equipped with ventilators, gas detectors, fire extinguisher (for example, of a carbon dioxide type), and the like to provide for gas explosion.

A numerical reference 57 indicates cargo oil suction pipes, which are located at a bottom portion of the wing cargo tanks 36 to extend toward the pump room 16.

In the above-described embodiment, passages 42 are sandwiched between the longitudinal bulkheads and the cargo hatch, FIG. 5 shows another passage arrangement, where the passages are located in contact with the side ballast tanks 28, and the outer side of the passage 42 is defined by an inner wall 29 of the side ballast tank 28. Piping disposition in the passage 42 are the same as those in the case of FIG. 3.

FIG. 6 is the case for a pure oil tanker. Since it has no cargo hatches, a single passage 42 is provided along a center line of a hull as shown with chain lines in the drawing, in which a cargo delivery pipe, an inert gas pipe, and other pipes are accommodated, Instead of centerline passage, two passages 42 may be located at both sides symmetrically and in contact with side ballast tanks as shown with solid lines in the same drawing.

FIG. 7 shows an embodiment of an OBO, that is, oil/bulk/ore carrier. Piping passages 42 are formed between side ballast tanks 28 and cargo hatches 38. In this kind of the vessel, the cargo hatch is so wide that hatch side space on upper deck is very narrow. So it is of a great advantage to provide piping passages under the upper deck. 

1. A piping structure for an oil tanker comprising: a piping passage longitudinally extending inside a hull of the tanker, said passage being surrounded by watertight structures and particularly an inside top portion thereof being formed by the upper deck; and a cargo delivery pipe being run through said passage, said delivery pipe interconnecting a pump room at an aft portion of the hull and a shore-connection provided amidship on the upper deck.
 2. A piping structure defined in claim 1 wherein said piping passage is extended to a bow portion of the hull and houses an inert gas pipe therein for delivering an inert gas from an inert gas generator disposed in an aft portion of the hull to each cargo oil tank.
 3. A piping structure defined in claim 1 or 2 further comprising: a longitudinal bulkhead extending to divide an inside space of the hull into a plurality of cargo oil tanks; and said piping passage extending along and in contact with said longitudinal bulkheads, one side of said passage being formed by said longitudinal bulkhead.
 4. A piping structure defined in claim 1 or 2 further comprising: cargo hatches for loading solid cargo disposed on the upper deck; and hatch side girders attached to a lower side of the upper deck in the manner to pass along each side of said cargo hatches, said girders each forming one side of said passage.
 5. A piping structure defined in claim 1 or 2 further comprising: side ballast tanks being provided in the hull; and said piping passage being disposed in contact with said side ballast tanks, and one side of said passage being formed by an inner wall of said side ballast tank.
 6. A piping structure for oil tanker defined in claim 1 or 2 wherein the size of said passage is such as to allow men to pass through.
 7. A piping structure for oil tanker defined in claim 1 or 2 wherein said passage is provided with a plurality of doorways leading up to the upper deck. 